Union County Average 1999 NATA Modeled Air Concentrations Compared to Health Benchmarks

Pollutant

Modeled
Air Concentration (ug/m3)

Health
Benchmark (ug/m3)

Risk
Ratio

%
Contribution from

Major Sources

Area
Sources

On-road
Mobile Sources

Nonroad
Mobile Sources

Background

Acetaldehyde

2

0.45

5

2%

5%

59%

13%

21%

Acrolein

0.2

0.020

12

0.09%

23%

48%

29%

0%

Arsenic Compounds

0.0001

0.00023

0.4

6%

94%

0%

0%

0%

Benzene

2

0.13

16

0.5%

10%

53%

14%

22%

Bis(2-ethylhexyl)phthalate

2

0.42

4

0.2%

0.05%

0%

0%

100%

1,3-Butadiene

0.2

0.033

6

0.05%

4%

41%

20%

35%

Cadmium Compounds

0.00008

0.00024

0.3

14%

85%

0%

0.9%

0%

Carbon Tetrachloride

0.3

0.067

4

0.01%

0.5%

0%

0%

99%

Chloroform

0.1

0.043

3

0.3%

67%

0%

0%

33%

Chromium (hexavalent form)

0.0001

0.000083

1.5

21%

64%

14%

0.5%

0%

1,4-Dichlorobenzene

0.09

0.091

1

4%

96%

0%

0%

0%

1,3-Dichloropropene

0.2

0.25

0.7

0%

100%

0%

0%

0%

Diesel Particulate Matter

2

0.0033

664

0%

0%

39%

61%

*

Ethylene Dibromide

0.03

0.0017

19

0.07%

0.02%

0%

0%

100%

Ethylene Dichloride

0.05

0.038

1.2

1%

0.3%

0%

0%

99%

Ethylene Oxide

0.007

0.011

0.6

16%

84%

0%

0%

0%

Formaldehyde

3

0.077

34

2%

4%

39%

22%

34%

Methyl Chloride

1

0.56

2

0.04%

1%

0%

0%

99%

Naphthalene

0.1

0.029

5

2%

69%

19%

10%

0%

Nickel Compounds

0.002

0.0064

0.3

3%

93%

3%

0.5%

0%

Perchloroethylene

0.3

0.17

1.9

0.6%

58%

0%

0%

41%

1,1,2,2-Tetrachloroethane

0.07

0.017

4

0.2%

0.7%

0%

0%

99%

Chemicals with risk ratios greater than or equal to 1 are
in bold.
Risk Ratios in italics are based on noncarcinogenic effects.
The symbol ug/m3 is micrograms per cubic meter,
the amount (in micrograms) of a chemical in a cubic
meter of air. This is also known as a concentration.
* For diesel particulate matter, onroad and nonroad
concentrations include a model-estimated background
concentration.